Fan

ABSTRACT

This is related to a fan including a casing, a first impeller structure, a second impeller structure, and at least one driving device. The casing has an outlet and an air-containing portion having an entrance and an exit provided inside the casing. The first impeller structure and the second impeller structure are installed inside the casing, and include a first blade set and a second blade set, respectively. The first blade set is located corresponding to the entrance of the air-containing portion. The second blade set is located corresponding to the exit of the air-containing portion. The driving device drives the first and second impeller structures.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a fan and, in particular, to a centrifugal fan.

2. Related Art

In the conventional electrical system, the electrical component, such asa CPU, is usually provided. The electrical component generates heat andmay have lower performance at the high temperature. In such a case, tomaintain the acceptable performance of the electrical component, thegenerated heat must be removed as soon as fast. To achieve thisobjective, a blower is usually adopted to dissipate heat quickly.

In the present, there are two most popular fans including the axial fanand the centrifugal fan (or the blower). Since the centrifugal fanprovides airflow with higher pressure, it can achieve better heatdissipating effect. Thus, the centrifugal fan has become the majortrend. As shown in FIG. 1, the conventional centrifugal fan 1 includes acasing 11, an impeller structure 13 and a driving device 15. The casing11 has an axial inlet and an outlet 111, and the impeller structure 13and driving device 15 are installed inside the casing 11. The blade set131 of the impeller structure 13 is located corresponding to the outlet111. In this case, when the driving device 15 drives the impellerstructure 13 to rotate, the blade set 131 presses the air to generatethe airflow through the outlet 111.

However, the centrifugal fan 1 can only provide a single pressing, sothe pressure increasing effect of the centrifugal fan 1 is limited.

It is therefore an important subject of the invention to provide acentrifugal fan that can enhance the pressure increasing effect.

SUMMARY OF THE INVENTION

In view of the foregoing, the invention is to provide a centrifugal fanthat can efficiently enhance the pressure increasing effect.

To achieve the above, a centrifugal fan of an embodiment of theinvention includes a casing, a first impeller structure, a secondimpeller structure, and at least one driving device. In the embodimentof the invention, the casing has an outlet and at least one firstair-containing portion, which has a first lateral entrance and a firstexit, provided inside the casing. The first impeller structure and thesecond impeller structure are installed inside the casing, and include afirst blade set and a second blade set, respectively. The first bladeset is located corresponding to the first lateral entrance of theair-containing portion. The second blade set is located corresponding tothe first exit of the air-containing portion. The driving device drivesone of the first and second impeller structures.

As mentioned above, the casing of the centrifugal fan of the inventionhas the air-containing portion for enhancing the pressure increasingeffect. As a result, the heat dissipating ability of the centrifugal fanof the invention can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detaileddescription given herein below illustration only, and thus is notlimitative of the present invention, and wherein:

FIG. 1 is a schematic view showing the conventional centrifugal fan;

FIG. 2 is a schematic view showing a centrifugal fan according to apreferred embodiment of the invention; and

FIG. 3 is a schematic view showing a centrifugal fan according toanother preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings,wherein the same references relate to the same elements.

With reference to FIG. 2, a centrifugal fan 2 according to a preferredembodiment of the invention includes a casing 21, an impeller structure23, an impeller structure 25, and at least one driving device 27.

The casing 21 has an outlet 211 and an axial inlet 212. Anair-containing portion 213, which has a lateral entrance 213 a and anexit 213 b, is disposed inside the casing 21. In this embodiment, theair-containing portion 213 is an annular space located at the upper ofthe interior of the casing 21. The air-containing portion 213 is usedfor temporarily storing the air so as to provide the air accumulatingfunction.

Furthermore, the air-containing portion 213 has a vortex offsettingelement 213 c located at the position that the vortex may occur insidethe air-containing portion 213. For example, the vortex may appear atthe corner or the exit 213 b inside the air-containing portion 213. Inthis case, the vortex offsetting element 213 c can eliminate the vortexcaused by the air flowing through the air-containing portion 213. Sincethe vortex may reduce the air accumulating function of theair-containing portion 213, the configuration of the vortex offsettingelement 213 c for eliminating the vortex can maintain the airaccumulating function of the air-containing portion 213. In the presentembodiment, the vortex offsetting element 213 c is a rib, a platestructure, or a curved structure. Besides, there can be a plurality ofvortex offsetting elements 213 c disposed inside the air-containingportion 213 for further enhancing the effect of eliminating the vortex.

As shown in FIG. 2, the impeller structure 23 is disposed in the casing21 and has a blade set 231, which is located corresponding to theentrance 213 a of the air-containing portion 213. In addition, theimpeller structure 25 is also disposed in the casing 21 and has a bladeset 251, which is located corresponding to the exit 213 b of theair-containing portion 213 and the outlet 211 of the casing 21. In thecurrent embodiment, the impeller structures 23 and 25 are seriallyarranged and are both either centrifugal impellers or axial-flowimpellers, respectively. The diameter of the impeller structure 25 isgreater than that of the impeller structure 23. The blades of the bladesets 231 and 251 are rectangular, polygonal, L-shaped, or the likes, andthe blades may have any preferred shape with curved corners. Moreover,to enhance the airflow pressing effect of the impeller structure 25, theblade set 251 of the impeller structure 25 is preferably L-shaped.Besides, the blades of the blade sets 231 and 251 may have curvedcorners, and the extension directions from the ends of the blade sets231 and 251 are perpendicular to the axial direction of the blade sets231 and 251.

The driving device 27 is disposed in the casing 21 and drives theimpeller structures 23 and 25. In the embodiment, the impellerstructures 23 and 25 are pivoted to the driving device 27, respectively.Accordingly, the driving device 27 is disposed inside the impellerstructure 23 or 25 and can simultaneously drive the impeller structures23 and 25. Alternatively, the driving device 27 may only drive one ofthe impeller structures 23 and 25. Then, the other one of the impellerstructures 23 and 25 that is not driven by the driving device 27 isdriven by the one driven by the driving device 27. In addition, thedriving device 27 and another driving device (not shown) may be used todrive the impeller structures 23 and 25, respectively.

In this embodiment, when the driving device 27 drives the impellerstructure 23 to rotate, the impeller structure 23 sucks the air from theinlet 212 and then blows the air into the air-containing portion 213through the entrance 213 a. After that, the air flows from theair-containing portion 213 to the blade set 251, and the blade set 251blows the air out through the outlet 211. As mention above, the vortexoffsetting element(s) 213 c disposed inside the air-containing portion213 may properly eliminate the vortex. In this case, since the impellerstructure 23 presses the air, the air flowing toward the blade set 251from the exit 213 b of the air-containing portion 213 has a pressuregreater than the external pressure such as the pressure at the inlet212. When the impeller structure 25 presses the air from the exit 213 bof the air-containing portion 213 and blows the air out through theoutlet 211, the air through the outlet 211 can be further pressed so asto obtain the air of higher pressure.

To be noted, the centrifugal fan of the invention is not limited to theabove-mentioned embodiment. For example, the first impeller structurecan be an axial-flow impeller structure (not shown) and the secondimpeller structure is a centrifugal impeller structure. Besides, thecentrifugal fan of the invention may include a plurality of drivingdevices (not shown) for driving different impeller structures such asthe previously mentioned impeller structures 23 and 25.

Furthermore, the centrifugal fan of the invention may include aplurality of impeller structures and a plurality of air-containingportions, such as three impeller structures and two air-containingportions, four impeller structures and three air-containing portions, orfive impeller structures and four air-containing portions. Moreover,multiple impeller structures may correspond to the same air-containingportion, so that the centrifugal fan of the invention may include fiveimpeller structures and two air-containing portions. To make theinvention more comprehensive, an example of the centrifugal fan havingthree impeller structures and two air-containing portions is describedhereinafter.

With reference to FIG. 3, a centrifugal fan 3 according to anotherpreferred embodiment of the invention includes a casing 31, an impellerstructure 33, an impeller structure 35, an impeller structure 39, and atleast one driving device 37. Comparing the present embodiment and theprevious embodiment, the centrifugal fan 3 of the present embodiment hasmore air-containing portions for enhancing the air pressure at theoutlet by multiple pressing. In this embodiment, the only concern forthe dimensions of the impeller structures is that the impeller structure39 must have greater diameter than that of the impeller structure 35.Herein, the blades of the blade set 391 of the impeller structure 39 arerectangular, polygonal, or L-shaped, and the blades of the blade sets331 and 351 of the impeller structures 33 and 35 can also berectangular, polygonal, or L-shaped. The blades may have any preferredshape with curved corners.

The operation of the centrifugal fan 3 of this embodiment will bedescribed hereinafter. In this embodiment, the casing 31 has a lateraloutlet 311 and an axial inlet 312. An air-containing portion 313, whichhas a lateral entrance 313 a, a lateral exit 313 b and a vortexoffsetting element 313 c, and an air-containing portion 315, which hasan entrance 315 a, an exit 315 b and a vortex offsetting element 315 c,are disposed inside the casing 31. In this embodiment, theair-containing portions 313 and 315 are two stacked annular spaceslocated at the upper of the interior of the casing 31. Theair-containing portions 313 and 315 are used for temporarily storing theair so as to provide the multi-step air accumulating function.

The impeller structures 33, 35 and 39 are disposed in the casing 31 andhave the blade sets 331, 351 and 391, respectively. In this case, theblade set 331 is located corresponding to the entrance 313 a of theair-containing portion 313. The blade set 351 is located correspondingto exit 313 b of the air-containing portion 313 and the entrance 315 aof the air-containing portion 315. The blade set 391 is locatedcorresponding to the exit 315 b of the air-containing portion 315 andthe outlet 311 of the casing 31. In the current embodiment, the impellerstructures 33, 35 and 39 are serially arranged.

In the present embodiment, the impeller structures 33, 35 and 39 aresimultaneously driven by the driving device 37. Of course, the drivingdevice 37 may only drive one of the impeller structures 33, 35 and 39,and the driven impeller structure is used to drive the residual impellerstructures. When the impeller structures 33, 35 and 39 rotate, theimpeller structure 33 sucks the air from the inlet 312 and then blowsthe air into the air-containing portion 313 through the entrance 313 a.After that, the impeller structure 35 sucks the air from the exit 313 bof the air-containing portion 313 and then blows the air into theair-containing portion 315 through the entrance 315 a. Finally, theimpeller structure 39 sucks the air from the exit 315 b of theair-containing portion 315 and then blows the air out through the outlet311. In this case, the pressure in the air-containing portion 315 isgreater than that in the air-containing portion 313, and the pressure inthe air-containing portion 313 is greater than the external pressuresuch as the pressure at the inlet 312. Thus, the impeller structures 33,35 and 39 can a provide two-step pressing effect, which can emphasizethe pressing effect.

In summary, the casing of the centrifugal fan of the invention has theair-containing portion, such as the air-containing portion 213, 313 or315, for enhancing the pressure increasing effect. Moreover, theinvention can provide the multi-step pressing effect. As a result, theheat dissipating ability of the centrifugal fan of the invention can beimproved.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiments, as well asalternative embodiments, will be apparent to persons skilled in the art.It is, therefore, contemplated that the appended claims will cover allmodifications that fall within the true scope of the invention.

1. A fan, comprising: a casing having a first air-containing portiondisposed therein, wherein the air-containing portion comprises a firstentrance and a first exit; a first impeller structure installed insidethe casing and comprising a first blade set, wherein the first blade setis located corresponding to the first entrance of the firstair-containing portion; and a second impeller structure installed insidethe casing and comprising a second blade set, wherein the second bladeset is located corresponding to the first exit of the firstair-containing portion.
 2. The fan of claim 1, wherein the firstair-containing portion comprises at least one first vortex offsettingelement for eliminating a vortex caused by air flowing through the firstair-containing portion.
 3. The fan of claim 2, wherein the first vortexoffsetting element is a rib, a plate structure, or a curved structure.4. The fan of claim 2, wherein the first vortex offsetting element islocated at a corner of the first air-containing portion or the firstexit of the first air-containing portion.
 5. The fan of claim 1, whereina diameter of the second impeller structure is greater than that of thefirst impeller structure.
 6. The fan of claim 1, further comprising atleast one first driving device for driving one of the first impellerstructure and the second impeller structure.
 7. The fan of claim 6,wherein the first driving device is disposed inside the first impellerstructure and simultaneously drives the first impeller structure and thesecond impeller structure.
 8. The fan of claim 6, further comprising: asecond driving device, wherein the first driving device and the seconddriving device respectively drives the first impeller structure and thesecond impeller structure.
 9. The fan of claim 6, wherein the firstdriving device drives one of the first impeller structure and the secondimpeller structure; and the other one of the first impeller structureand the second impeller structure that is not driven by the firstdriving device is driven by the first impeller structure or the secondimpeller structure, which is driven by the first driving device.
 10. Thefan of claim 1, wherein the first impeller structure and the secondimpeller structure are centrifugal impellers or axial-flow impellers,respectively.
 11. The fan of claim 1, wherein the first impellerstructure and the second impeller structure are serially arranged. 12.The fan of claim 1, wherein the blades of the first blade set or thesecond blade set are rectangular, polygonal, or L-shaped, and the bladeshave a shape with curved corners.
 13. The fan of claim 1, wherein anextension direction from the end of the first blade set or the secondblade set is perpendicular to the axial direction of the first blade setor the second blade set.
 14. The fan of claim 1, further comprising: atleast one second air-containing portion disposed in the casing andhaving a second entrance and a second exit; and at least one thirdimpeller structure disposed on the first impeller structure andcomprising a third blade set, wherein the third blade set is locatedcorresponding to the second entrance of the second air-containingportion, and the first blade set is further located corresponding to thesecond exit of the second air-containing portion.
 15. The fan of claim14, wherein the second air-containing portion has a pressure greaterthan an external pressure, and the first air-containing portion has apressure greater than that of the second air-containing portion.
 16. Thefan of claim 14, wherein the third impeller structure is a centrifugalimpeller structure or an axial-flow impeller structure.
 17. The fan ofclaim 14, wherein the blades of the third blade set are rectangular,polygonal, or L-shaped, and the blades have a shaped with curvedcorners.
 18. The fan of claim 14, wherein the second air-containingportion comprises at least one second vortex offsetting element foreliminating a vortex caused by air flowing through the secondair-containing portion.
 19. The fan of claim 18, wherein the secondvortex offsetting element is a rib, a plate structure, or a curvedstructure.
 20. The fan of claim 18, wherein the second vortex offsettingelement is located at a corner of the second air-containing portion orthe second exit of the second air-containing portion.